Motion film projector

ABSTRACT

A motion film projector which comprises an image plane and a gate for holding a frame of a motion picture film to be projected in the image plane. An optical system defines an optical axis, and the frame is located on the optical axis. A focusing device is provided for the optical system. A drive is arranged for feeding the film along a predetermined path including the image plane. The drive has at least two operating modes comprising at least one run mode and a still mode of operation for selectively providing motion picture projection and still picture projection. A focus adjuster is connected to the focusing device to provide a basic adjustment of the same for focusing the frames of the film during the run mode oepration. A mode selector controls the operating modes of the drive and has accordingly at least one run mode position and a still mode position. A coupling member is provided to connect the focusing device to the mode selector. The mode selector further has a plurality of focusing positions adjacent the still mode position. In the focusing positions the coupling member connects the focusing device to the mode selector to override the basic adjustment and to focus the frame individually during the still mode operation.

United States Patent 91 Wessner 11 3,785,727 451 Jan. 15, 1974 1 1MOTION FILM PROJECTOR 1 [75] lnventor: Harald Wessner ,Neunkirchen,

Austria [73] Assignees: Karl Vockenhuber; Raimund Hauser, both ofVienna, Austria 22 Filed: Oct.5, 1972 211 Appl.No.:295,'296

[30] Foreign Application Priority Data Primary Examiner-Joseph F.Peters, Jr. Assistant Examiner-Alan Mathews Att0rneyErnest G. Montague I[57] ABSTRACT A motion film projector which comprises an image plane anda gate for holding a'frame of a motion picture film to be projected inthe image plane. An optical system defines an optical axis, and theframe is located on the optical axis. A focusing device is provided forthe optical system. Adrive is arranged for feeding the film along apredetermined path including the image plane. The drive has at least twooperating modes comprising at least one run mode and a still mode ofoperation for selectively providing motion picture projection and stillpicture projection. A focus adjuster is connected to the focusing deviceto provide a basic adjustment of the same for focusing the frames ofthe'film during the run mode oepration. A mode selector controls theoperating modes of the drive and has accordingly at least onerun modeposition and a still mode position. A coupling member is provided toconnect the focusing device to the mode selector. The mode selectorfurther has a plurality of focusing positions adjacent thestill modeposition. In the focusing positions the coupling member connects thefocusing device to the mode selector to override the basic adjustmentand to focus the frame individually during the still mode operation.

8 Claims, 9 Drawing Figures SHEET 2 BF 4 FIG 2 PATENTEUJAN 1 5l974MOTION FILM PROJECTOR The invention relates to a motion film projectorwith a projection lens and two focusing means operable independentlyfrom each other for adjusting the projection lens or an optical memberthereof relatively to the position of the film, whereby one of thefocusing means and a device for standstill projection are actuated by asingle operating mechanism.

It is known that at standstill projection of motion picture films inprojectors, the disadvantage 'occurs that the emulsion layer of the filmdries out due to the heat given off by the projection lamp andconsequently the picture lying in the film gate gets vaulted. Thereproduction is then no longer sharp and an adjusting focusing of thelens becomes necessary. Due to the previous adjustmentof the lens arenewed focusing is required at the following projection with runningfilm to reestablish the original setting.

In order to avoid these disadvantages, an arrangement controlled by anelectromagnet has become known, which effects a focusing of the lens atstandstill.

After the standstill projection the magnet is again deenergized, theanchor falls off and the setting device for the lens connected with theanchor reestablishes the original focusing. The high expenditure ofstructural members, respectively, the complicated mechanism of thetransmission gear from the anchor to the focusing means turns out to bevery disadvantageous. In addition, the amount of the adjusting focusingat standstill is constant, due to the predetermined position of theattracted anchor, independent of whether the image is really sharp ornot. Another known arrangement provides a plane parallel glass plateinserted in the path of rays of projection between the film gate and theprojection lens for adjusting focusing at standstill. Besides thedisadvantage of the adjusting focusing by a fixed amount there results afurther disadvantage, namely with respect to the thickness of the glassplate, because by this glass plate the small light intensity prevailingat standstill already by the inserted heat insulating filter betweenprojection lamp and film gate is further reduced.

According to the invention it is suggested that the operating mechanismin an equipment of the kind mentioned above has following the positionstandstill, a focus adjusting range for the continuous focusing ondifferent image positions of the film. In that way the image may befocused according to its effective position in the film gate, wherebythe'light intensity is not influenced. Upon following the projectionwith running film, the original focusing of the lens is immediatelyreestablished. Moreover the structural expenditure of this arrangementis very small.

In order to reduce the heat emanated by the projection lamp in thedirection of the film, it is advantageous to connect a heat insulatingfilter to the operating mechanism, as it is already known, whereby theheat insulating filter is switchable in the position standstill in thepath of rays of the projection lens.

According to a further advantageous embodiment of the invention it issuggested that the operating mechanism shows a plurality of switchpositions, which, arranged with respect to their amount, correspond withdifferent image frequencies, whereby one extreme working position of theoperating mechanism corresponds with the largest image frequency,whereas the other extreme position corresponds with standstillprojection. At the same time the operating mechanism could in that waybe connected'with a device controlling the film drive with variableimage frequency.

Further advantages and details of the invention will become apparentfrom the specification of schematically illustrated embodiments in theattached drawings. FIG. 1 shows a variation of the inventive embodiment,whereby FIG. 1A represents a partial front elevation of FIG. 1. FIG. 2displays a further embodiment of the invention. FIGS. 3 to 6 showembodiments of arrangements for coarse and fine setting of the lens.

FIG. 1 shows schematically the contours of a projector 1, in which alens 2 reproduces a film 4 illuminated by a light source 3 on aprojection plane, not shown. The casing of the lens 2 is shiftable in astraight guide fixed to the projector and shows has a ring-shaped groove5, in which a guide pin 6 which is fixed to a lever 7 is guided freefrom play. The lever 7 bears a further pin 8 on its end lying oppositethe fixation of the guide pin 6. Between these two pins 6 and 8, athreaded sleeve 10 is pivotally arranged around an axis 9 of the lever7. The threaded sleeve 10 cooperates with a threaded coupling pin 1 1pivotally arranged in the projector casing, which is provided on thefront surface of the casing with a setting knob 12. The bearing of thethreaded coupling pin 11 in the casing 1 secures it against axialshifting. As the lever 7 is forced by a tension spring 13 fixed on thecasing 1 in the direction of the projection plane, it abuts a fixed stop14.

If at the beginning of motion picture projection the lens 2 is focused,the setting knob 12 is turned, which causes a shifting of the threadedsleeve 10, which is pivoted to the lever 7 along the threaded couplingpin 11. The stop 14 functions here as a point of rotation for the lever7. The movement of the lever 7 is transmitted to the lens 2 by the pin6.

In order to regain the sharpness of reproduction,

which has been lost at standstill projection because of the bending ofthe film image standing in the film gate, an arrangement for focusadjustment of the lens is disposed under the setting knob 12. Thisarrangement is formed by a lever 15, which is pivotally arranged roundan axis 16 and has an extension 17 in the immediate neighbourhood of thepin 8 of the lever 7. Theend of the lever 15 extending through theprojector casing l is guided in a slot 18 of the casing wall (see FIG.1A). A rod 19 shiftable in transverse direction to the optical axis ofthe lens 2 bears a mount 20 for a heat insulating filter 21. This rod is19 connected at one end with the lever 15 is charged at the opposite endby a tension spring 22, which is fixed to the casing. By this tensionspring 22, the lever 15 is held at the same time at the I upper end ofthe slot 18 (related to FIG. I), which corresponds to the position fornormal projection (for instance 18 frames per sec.).

At standstill projection the lever 15 is pressed downwardly against theaction of the tension spring 22 along the slot 18 until it reaches themark zero on the casing wall. Upon reaching this mark, nothing has yetchanged in the setting of the lens. Onlyupon further moving down of thelever 15 (until the mark foc.us) the extension 17 abuts the pin 8 of thelever 7 and upon renewed downwards movement of the focusing lever 15, itremoves the lever 7 from the stop 14. The lever 7 is turned round theaxis 9 of the threaded sleeve 10 fixed to the threaded coupling pin 11and shifts the lens 2 tion by the action of the spring 22, whereby thefilter 21 is removed from the path of rays and the lever 7 1 again abutsthe stop 14. In that way the adjustment of the lens 2 is againreestablished before standstill projection. Arrangements known per seand therefore not illustrated are connected with the lever 15, in orderto change, at the same time by its actuation, the frame frequency from18 frames per sec., in case over 9 frames per sec. to standstillprojection.

In FIG. 2 a further inventive embodiment is schematically illustrated.The pin-slot guide 5, 6 of the embodiment described above is herereplaced by a toothed rack-toothed segment guide 23, 24. Atfocusing innormal operation a lens hearing the toothed rack 23 is deviated by thetoothed segment 24 in the direction of the optical axis. A portion 26bearing the toothed segment 23 is provided with a rectangular leverextension 27, whereby the portion 26 itself is pivotally arranged rounda fixed axis 29, which also supports a focus setting lever 28. The focussetting lever 28 bears a further axis 30 for a two-armed transmissionlever 31, whereby one end of the lever 31 is flexibly connected with theextension 27. A pin 32 fixed on the focus setting lever 28 engages aslot 33 milled in an arm 34 of an angle 35. The other arm'of the anglelever 35 resiliently abuts an oblique surface 36 of the portion 26bearing the segment. As the angle 35 is likewise pivotally arrangedround a fixed axis 37, the portion 26, the focus setting lever 28 andthe angle lever 35 form a sort of quadrilateral bellcrank.

Upon focusing of the lens 25 the focus setting lever 28 is now forinstance moved downwards related to FIG. 2 whereby this lever 28 isturned round the axis 29. Due to the oblique slot 33, the arm 34 of theangle lever 35 is moved to the right, the arm abutting the obliquesurface 36 is moved downwards. That way the portion 26 bearing thesegment 24 is turned to the right related to FIG. 2 and shifts the lens25 by means of the toothed rack 23.

A setting lever for frame frequency 40, which is provided directly nearthe focus setting lever 28, is during normal projection in thedash-lined position 40'. At standstill projection, the lever 40 ispressed downwards related to FIG. 2 whereby a stop 39 of the lever 40abuts the other end of the two-armed lever 31. In order to enable thenow required adjusting focusing of the lens for sharper reproduction,the lever 40 is further pressed downwards. By the stop 39 the two-armedlever 31 is turned, which again transmits the movement over the end,which is flexibly connected with the extension'27 to the portion 26bearing the toothed segment 24. Again related to FIG. 2, the portion 26moves against the action of a spring 38 to the left and adjusts the lensby the desired amount. Upon release of the focusing lever 28, it reachesagain the mark zero by the force of the spring 38. The original focussetting has not .been changed, because the position of the pin 32 in theoblique slot 33 remained unaltered.

Theoretically it would be possible to design the arrangement in such amanner that the lens could be shifted in both directions. Since howeverin a projector the position of the emulsion layer of the film withrespect to the position of the projection lamp remains always the same,the film will bend at standstill projection always in the samedirection. Therefore an adjusting focusing of the lens its onlynecessary in one direc' tion.

Preferably the lever for adjusting focusing itself is designed as modecontrol switch or at least it is directly connected with the same. Agroove provided in the guide of the lever could then correspond with theposition for projection with another frame frequency (for instance 9frames per sec.). With this lever a cam follower or a cam could then atthe same time be controlled for the meshing stroke of the claw.

Further possibilities of design for the focus setting lever 28illustrated in FIG. 2 are displayed in FIGS. 3

In FIG. 3 a lever corresponding to the focus setting lever 28 is markedwith the reference numeral 41. This lever 41 is pivotally arranged rounda fixed axis 43 together with an angle 42, whereby the connectionbetween the angle 42 and the focusing lever is carried out over a pin 44of the lever 41. The pin 44 is situated in a slot guide 45 of the angle42, which angle equals in its function the portion 26 illustrated inFIG. 2, that is for adjusting the lens 25.

Besides the pin 44 the focusing lever 41 shows two slot guides 46, 47,in the first of which there is arranged the axis 43 and a pin 48 of afriction lever 49, which is likewise tiltable round the axis 43, isassigned to the guide 47. Generally considered the focusing lever isshiftable along the slot guides 46, 47 in the direction of the arrow Aand tiltable round the axis 43 in the direction of the arrow B.

If the focusing lever 41 is in the position in which the axis 43 issituated at the right end of the slot 46 related to FIG. 3 a deviationof the lever 41 in the direction B causes an adjustment of the lens 25,in that the angle 42 controlling the lens 25 over a ball guide isdeviated by the lever 41 over the pin 44. The transmission with whichthe lens is adjusted relatively to the deviating angle of the lever 41depends on the distance 9 between the axis 43 and the pin 44. Upondeviation also the friction lever 49, which meshes with the slot 47 ofthe focus setting lever 41 over the pin 48, is taken along. A bearing 50of the lever 49 on the axis 43 (see FIG. 3A) causes by its highly setbearing friction a heavy previous focusing of the lens.

If the lever 41 is pulled to the right related to FIG. 3 the axis 43arrives in a widening 51 of the slot 46. At the same time the pins 44and 48 occupy the dashlined position of FIG. 3, in which they areremoved from each other in a distance b." Upon turning of the lever 41,the centre of gravity is no more the axis 43 situated in the widening51, but the pin 48 of the friction lever 49. The reason why this ispossible is, as already set forth, that the bearing 50 fits with heavyfriction to the axis 43, so that upon deviation of the lever 41 thefriction lever 49 remains in its position. The focusing of the lens 25is effected over the pin 44 of the focusing lever 41 and the angle 42.As the now working lever arm b is much smaller than the previouslyworking arm a, also a fine setting of the lens becomes possible.

A variation slightly differing from the construction of FIGS. 3, 3A isillustrated in FIGS. 4, 4A, whereby parts of the same function aremarked with the same reference numerals.

The focusing lever 41 is not tiltable round the axis 43, but bears pins51 and 52. The pin 51 is assignedto a slot 53, the pin 52 to a slot 54'of the angle 42. Between the two pins the focusing lever 41 shows alonghole 55 (see FlG. 4A), which supports an axis 48a of the frictionlever 49. A pressure spring 56 on the axis 48a secures the frictionlever 51 against a collar 57 of the axis 48a.

The focusing lever 41 tiltable round the axis 48a in the direction ofthe arrow B is further tiltable along the axis 48a in the direction ofthe arrow C against the action of the spring 56 (see FIG. 4A). Upon thisdeviation in the direction C only the pin 51 meshes with the slot 53 ofthe angle 42, whereas in the rest position also the pin 52 engages theslot 54.

If now the focusing lever 41 is tuened in the position in which also thepin 52 engages the slot 54 in the direction of the arrow B, the frictionlever 49 as well as angle 42 are taken along, whereby again the frictionin the bearing 50 causes a relatively heavy displacement of the lens 25.In that way it is secured that the focusing lever 41 does not cause adisplacement of the lens by its own weight. In this coarse setting theoperative. lever length is again marked by a.

If the focusing lever 41 is turned in the direction of the arrow Cagainst the action of the spring 56, the pin 52 disengages the slot 54.A focusing in this position causes a turning of the lever 41 round theaxis 48a of the friction lever 49 kept in friction. Herewith the pin 51of the lever 41 arranged in a distance b from the axis 48a transmits themovement to the angle 42 and consequently to the lens 25. since, as inthe'embodiment shown in FIG. 3, the lever length b is much smaller thanthe length a, again a fine setting of the lens 25 becomes possible inthe last described position of the focusing lever 41.

FIG. 5 displays a much simplified form of an arrangement for coarse andfine setting of the lens. Instead of the focusing lever 41 a focusingspindle 58 is provided in this construction, on the end of which thereis fastened a transmission lever, which is tiltable round a fixed axis59. The transmission lever 60 is as usual coupled with the lens carrier,for instance over a ball seat. Further an angle 61 is tiltable round theaxis 59, which angle. shows a tab 62 provided with a threaded sleeve, inwhich the focusing spindle is guided.

For the coarse setting of the lens 25, the spindle 58 is turned in thedirection of the arrow B, whereby the angle 61 situated in a frictionbearing on the axis 59, turns round the axis 59 and likewise causes adeviation of the transmission lever 60 round the axis 59. In that waythe lens is preadjusted.

For fine setting one turns the focusing spindle, whereby thetransmission lever 60 is removed from or guided to the threaded tab 62,depending on the position of the same. The turning of the transmissionlever 60 occurs in a much smaller angle range as at coarse setting,sothat smaller adjusting ways aretransmitted on the lens.

Finally FIG. 6 shows a further simple embodiment, whereby an angle 63twistable on a fixed axis 64 is provided for coarse setting of the lens25. The angle 63 bears a tab 65 or 66 respectively, on each end, inwhich there is guided a flexible shaft 67. For the transmission of thedeviating movement of the angle 63, respectively of the rotatingmovement of the shaft 67, a roller 68 is shiftably and pivotallyarranged in a slot guide 69 in the lens casing.

For the coarse setting of the lens the angle 63 is deviated round theaxis 64, whereby the shaft 67 is guided at the angle 63 and meshes withthe roller and thus transmits the movement. For fine setting the shaftis turned, whereby the excentric coupling of the shaft 67 to the roller68 causes the fine setting. The angle 63 is during this operation againheld by the friction bearing 50.

What is claimed is:

1. In a motion film projector an image plane;

gate means for holding a frame of a motion picture film to be projectedin said image plane;

an optical system defining an optical axis, said frame being located onsaid optical axis;

focusing means for said optical system;

drive means for feeding said film along a predetermined path includingsaid image plane, said drive means having at least two operating modescomprising at least one run mode and a still mode of operation forselectively providing motion picture projection and still pictureprojection;

focus adjusting means connected to said focusing means to provide abasic adjustment of the same for focusing the frames of said film duringthe run mode operation;

' mode selecting means controlling the operating modes of said drivemeans and having accordingly at least one run mode position and a stillmode position; coupling means to connect said focusing means to saidmode selectingmeans;

said mode selecting means further having a plurality of focusingpositions adjacent said still mode position, in said focusing positionssaid coupling means connecting said focusing means to said modeselecting means to override said basic adjustment and to focus saidframe individually during the still mode operation.

2. A motion film projector as claimed in claim 1, wherein said modeselecting means are manually operable.

3. A motion film projector as claimed in claim 1, wherein said modeselecting means are continuously movable through said focusingpositions.

4. A motion film projector as claimed in claim 1 further comprisingbiasing means connected to said mode selecting means, to urge the sameout of said focusing positions towards said still mode position.

5. A motion film projector as claimed in claim 1 fur ther comprising aheat insulating member connected to said mode selecting means, in therun mode position of said mode selecting means said heat insulatingmember being out of the range of said optical axis, in said still modeposition and said focusing positions said heat insulating member beingmoved onto said optical axis.

6. A motion film projector as claimed in claim 1 further comprisingspring means connected to said focusing means and urging the lattertowards said basic adjustment.

7. A motion film projector as claimed in claim 4, which includes,

biasing means connected to said focusing means, and wherein said springmeans and said biasing means are identical. 8. A motion film projectoras claimed in claim 1, wherein said mode selecting means include twoextreme mode positions, at least one of which corresponds to the stillmode operation of said drive means.

. I t. I1 4

1. In a motion film projector an image plane; gate means for holding aframe of a motion picture film to be projected in said image plane; anoptical system defining an optical axis, said frame being located onsaid optical axis; focusing means for said optical system; drive meansfor feeding said film along a predetermined path including said imageplane, said drive means having at least two operating modes comprisingat least one run mode and a still mode of operation for selectivelyproviding motion picture projection and still picture projection; focusadjusting means connected to said focusing means to provide a basicadjustment of the same for focusing the frames of said film during therun mode operation; mode selecting means controlling the operating modesof said drive means and having accordingly at least one run modeposition and a still mode position; coupling means to connect saidfocusing means to said mode selecting means; said mode selecting meansfurther having a plurality of focusing positions adjacent said stillmode position, in said focusing positions said coupling means connectingsaid focusing means to said mode selecting means to override said basicadjustment and to focus said frame individually during the still modeoperation.
 2. A motion film projector as claimed in claim 1, whereinsaid mode selecting means are manually operable.
 3. A motion filmprojector as claimed in claim 1, wherein said mode selecting means arecontinuously movable through said focusing positions.
 4. A motion filmprojector as claimed in claim 1 further comprising biasing meansconnected to said mode selecting means, to urge the same out of saidfocusing positions towards said still mode position.
 5. A motion filmprojector as claimed in claim 1 further comprising a heat insulatingmember connected to said mode selecting means, in the run mode positionof said mode selecting means said heat insulating member being out ofthe range of said optical axis, in said still mode position and saidfocusing positions said heat insulating member being moved onto saidoptical axis.
 6. A motion film projector as claimed in claim 1 furthercomprising spring means connected to said focusing means and urging thelatter towards said basic adjustment.
 7. A motion film projector asclaimed in claim 4, which includes, biasing means connected to saidfocusing means, and wherein said spring means and said biasing means areidentical.
 8. A motion film projector as claimed in claim 1, whereinsaid mode selecting means include two extreme mode positions, at leastone of which corresponds to the still mode operation of said drivemeans.